Phase quantification in nanobainite via magnetic measurements and X-ray diffraction

Abstract

Accurate phase quantification of nanostructured bainitic steel is of impor tance because of the nature of its percolating structure that controls many of its mechanical properties. X-ray diffraction is the technique of choice for such analysis, but magnetic methods can be more rapid and less sensitive to defect structures. In this study, the phase volume fractions measured using both of these techniques for the specific mixtures associated with nanostructured bainite have been compared and contrasted. An expression which relates the volume fraction and the saturation magnetisation is obtained and its form is found to be consistent with previous work done on duplex stainless steels and TRIP steels. The fitting constants used in many of such analyses vary sig nificantly so an attempt is made to rationalise the differences by considering the factors that determine the intrinsic saturation magnetisation of ferrite.